The liquid crystal display device has a larger size, a lighter weight and lower power consumption than that of the cathode ray tube (CRT). Therefore, the liquid crystal display device can be used for a television receiver or a variety of electronic devices. The liquid crystal display device encloses liquid crystal between two transparent substrates of variable sizes and applies electrical voltage across two electrodes provided to the transparent substrates to change orientations of liquid crystal molecules and light transmittance for optical display of, for example, a preset image.
In the liquid crystal display device, the liquid crystal itself does not emit light, and thus a light source needs to be configured for emitting light onto a liquid crystal panel. The light source may be a side light system in which light is emitted from a lateral side of a back surface of the liquid crystal panel, or a backlight system in which light is emitted directly from a back side of the liquid crystal panel. The liquid crystal display device includes backlight units such as a light guide plate, a reflective sheet, a lens sheet or a light diffusing sheet, which are configured for guiding the light provided by the light source onto an entire surface of the liquid crystal panel from the back side of the liquid crystal panel.